Electrocatalysis synergism motivated by low energy d-orbitals at high spin state for long-lifespan Li-O₂ batteries

High-spin-state-driven electrocatalysis is an effective strategy for enhancing the performance of lithium–oxygen batteries (LOBs). However, most studies primarily focus on the filling of high energy e_g orbital and the associated catalytic enhancement. In this study, we demonstrate that the high spin state activates the low energy t_2g orbitals typically with poor catalytic activity and delivers efficient synergistic electrocatalysis with high energy e_g orbitals for LOBs. Ni doping induced the transition of the Co site to a high-spin configuration in Co₂V₂O₇. The high spin state generates unpaired electrons and enhances the band distribution of low energy t_2g orbitals near the Fermi level. The high-spin-state-motivated high energy d_z² and low energy d_xy orbitals deliver good orbital overlapping with the anti-bonding orbital of the key intermediate LiO₂ and discharge product Li₂O₂, thus improving the electron injection efficiency during adsorption of LiO₂/Li₂O₂ for rapid redox kinetics. Furthermore, the activated low energy orbitals exhibit better d-p orbital coupling with the reactants, achieving efficient charge transfer, optimized adsorption behavior, and low overpotentials during the ORR/OER process. As a result, The Ni-doped Co₂V₂O₇ (Ni-CVO) cathode achieved an ultralong lifespan of 585 cycles, approximately four times longer than the pure Co₂V₂O₇ cathode. This work demonstrates a novel electrocatalytic mechanism driven by the high spin state and provides a comprehensive perspective for designing highly efficient cathode catalysts for LOBs.